Implements such as razors or electric shavers for cutting or shaving hair are well known in the prior art. Most prior art shaving implements for cutting human facial hair are designed to cut hair close to skin level, and preferably beneath that level without nicking or cutting the skin.
Conventional powered shaving devices typically cut individual hairs into a plurality of small pieces, leading to a dusty debris. Further, the resulting shaved skin may comprise stubble hairs which have not been cut in a fully satisfactory way.
Various attempts have been made to overcome this problem. For example, an electric dry shaver is disclosed in U.S. Pat. No. 4,139,940 (Buras, Jr.) which has projections on the outer surface of the cutting foil to move and lift low lying facial hairs for cutting by underlying blades on a blade block. The blade block includes weights to cause the blade block to be unbalanced and to vibrate and move particularly in a lateral direction, which in turn causes vibration of the housing and of the foil.
Further, U.S. Pat. No. 3,863,338 (Wellinger) describes an electric shaver comprising two cutter sections mounted in axial alignment. The two cutter sections are mounted for linear reciprocation in an aligned end-to-end relationship to avoid transmission of unpleasant vibration to the user and to avoid an unpleasant sensation due to the vibration where the shaver contacts the skin.
Furthermore, U.S. Pat. No. 3,872,587 (Wellinger) discloses an electric shaver comprising two cutter parts which extend longitudinally and parallel to each other to avoid vibration of the shaver body in use for reasons of comfort and noise as well as for an enhanced battery life. The two cutter parts are continuously biased away from each other by two coil springs.
Also, U.S. Pat. No. 6,151,780 (Klein) describes a dry shaving apparatus comprising two inner cutters operatively associated with a common outer cutter and arranged to be driven by a drive element, respectively, in relative opposite directions and against the force of at least one spring element to avoid vibration and running noise. The spring elements acting on both inner cutters provide a permanent compensation of vibration of the inner cutters which are arranged in parallel one after the other.
U.S. Pat. No. 3,263,105 (Heyek) discloses dry shaving appliances wherein two independent cutters are each driven against a restoring spring, in order to keep the apparatus as free as possible from the mechanical vibrations produced by the motor.
Further, JP 54-387 discloses two axially aligned undercutters driven in antiphase, with a portion of the respective guide blocks interfitting in each other for guidance.
Finally, U.S. Pat. No. 2,440,061 (Page) discloses a dry shaver which comprises two end-to-end axially aligned undercutters which rotate in opposite directions due to a bevel gear arrangement.
However, conventional shaving apparatus often leaves stubble hair of a significant length in the shaved skin so that the user appears to be unshaved after a short period of time.